Rate the atrophy that matters — medial temporal (MTA), posterior (Koedam), frontal and anterior temporal — score small-vessel disease (Fazekas) and microbleeds, and exclude the treatable (NPH, tumour, subdural): structural MRI supports, it does not diagnose, the dementia subtype.
Orient first
- Alzheimer disease: hippocampal and medial temporal atrophy, posterior cingulate and precuneus atrophy (earlier in young onset).
- Frontotemporal dementia: asymmetric frontal and anterior temporal ("knife-edge") atrophy.
- Vascular: extensive white matter hyperintensity and lacunes; amyloid angiopathy: lobar microbleeds and superficial siderosis.
Acquire the study
- MRI brain: 3D T1 (for coronal reformats perpendicular to the hippocampus), FLAIR, T2, SWI, DWI.
The manoeuvre
- Coronal 3D T1 through the hippocampi: medial temporal atrophy score 0–4 each side (Scheltens — verify age norms).
- Sagittal and axial T1: posterior atrophy (precuneus, parietal sulci; Koedam score).
- Axial FLAIR: white matter hyperintensity (Fazekas 0–3), lacunes, strategic infarcts.
- SWI: number and distribution of microbleeds (lobar vs deep), superficial siderosis.
- Ventricles vs sulci: NPH pattern (Evans index > 0.3, tight high-convexity sulci, callosal angle < 90°).
- DWI: cortical ribboning — Creutzfeldt–Jakob disease.
What confirms it
- A pattern consistent with a clinical syndrome; molecular imaging and biomarkers support the subtype.
What licenses you to exclude it
- Normal age-adjusted scores do not exclude early neurodegeneration.
The classic misread
- Rating hippocampal atrophy on axial slices.
- Missing CJD because DWI was not reviewed.